Almost every consumer electronics device available today features a so-called standby mode of operation so that the device, even when turned ‘off’, is still receptive to control signals. The device can react at any time to a signal sent by a remote control unit to turn the device on again. Examples of such devices are televisions, satellite receivers, air-conditioners, video recorders, tuners, personal computers, etc. Usually, an easily visible ‘standby’ LED indicates to the user that the device is in standby mode. Being able to place a device in standby is generally regarded as practical and convenient, compared to the situation hitherto in which the user had to physically turn the device on or off at the mains switch.
When a device is placed in standby mode, a small amount of current is still drawn by, for instance, standby circuitry and a standby LED. A corresponding amount of ‘standby power’ is therefore consumed. Usually, the standby power is quite low, only a few watts, but particularly inefficient devices can consume up to 20 watts in standby mode. Many consumers are becoming aware of the negative impact on the climate caused by energy over-consumption, and would prefer to reduce the amount of unnecessary power dissipation. Since almost every household or office has several devices that are ‘turned off’ by placing them in standby mode, the total amount of standby power dissipated by the millions of devices around the globe is actually quite considerable.
However, it is to be expected that users would still wish to be able to turn on and off consumer electronics devices by means of a remote control, without having to physically turn the device off at the mains switch.
One way of reducing the amount of standby power might be to monitor the current drawn by the device, so that a decision can be reached, requiring without any user input, whether the device should be disconnected from the power supply. If only a minimal amount of current is drawn over a certain length of time, it could be assumed that the device is not in use, and the device can then be automatically disconnected from the mains power supply by a dedicated switch. However, this approach still involves some amount of power dissipation for the required current monitoring components, for instance a power supply for a timer circuit. Also, a certain amount of time should be allowed to elapse before actually disconnecting the device, and during this time, standby power is consumed. Furthermore, a module of the device for receiving signals from a remote control unit must continually be supplied with power so that the user can reactivate the device at any time. Such an interface could be powered by a battery instead of the mains power supply, but this would not alter the fact that current will still be drawn by the device, and power consumed.
Therefore, it is an object of the invention to provide a way of activating and deactivating a device such that the device draws no current when deactivated by remote control.